Rotary electrical machines have been required to downsize with high output, especially, to reduce the lengths of stator coil ends of their stators; these stator coil ends project from stator cores of the stators. Rotary electric machines meeting this requirement can be installed in vehicle's engine compartments with their capacities kept unchanged.
In order to meet the requirement, a rotary electric machine needs to reduce the lengths (heights) of stator coil ends of a stator thereof from a stator core of the stator while increasing the winding packing factor of the stator.
An example of conventional rotary electric machines, which installs therein an annular-shaped stator with a sequentially joined-segment stator coil designed to fulfill the need, is disclosed in the Japanese Unexamined Patent Publication No. 2003-18778.
In the rotary electric machine disclosed in the Patent Publication, each conductor segment of a sequentially joined-segment stator coil is made of a U-shaped plate-like conductor and is formed at its substantially middle portion with a crank portion without kinks. The crank portion causes one of both sides of the crank portion in the plate-like conductor to shift from the other thereof by a predetermined length substantially corresponding to a width of the plate-like conductor. This structure of the stator prevents each conductor segment from expanding in radial directions thereof.
The invention disclosed in the Patent Publication is effective in cases where the conductor segments are arrayed in the circumferential direction of the stator core and/or the conductor segments with the same structure are arranged in a radial direction of the stator core.
It is to be considered that the invention disclosed in the Patent Publication is applied to a rotary electric machine with a sequentially joined-segment stator coil in which pairs of different-sized conductor segments are arrayed in the circumferential direction of a stator core such that the different-sized (large-sized and small-sized) conductor segments of each pair are overlapped.
In this application example, however, even if the small-sized conductor segment of each pair is prevented from radially extending, it may be difficult to prevent the large-sized conductor segment of each pair from radially expanding. This radial expansion of the large-sized conductor segment of each pair may cause the coil ends of the stator coil to radially extend.